Android 之多线程断点续传之（一）

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第一步：从布局文件下手.main.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ProgressBar
android:id="@+id/progressBar1"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</ProgressBar>
<TextView
android:id="@+id/textView1"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<ProgressBar
android:id="@+id/progressBar2"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</ProgressBar>
<TextView
android:id="@+id/textView2"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CALL_PHONE" />
<uses-permission android:name="android.permission.SEND_SMS" />
<uses-permission android:name="android.permission.READ_CONTACTS"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>

第二步：看看Activity
public class MainActivity extends Activity {
private ProgressBar pb1 = null;
private TextView tv1 = null;
private ProgressBar pb2 = null;
private TextView tv2 = null;
private String root = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator;
private String downloadFile = "http://gongxue.cn/yingyinkuaiche/UploadFiles_9323/201008/2010082909434077.mp3";
private String downloadFile1 = "http://gongxue.cn/yingyinkuaiche/UploadFiles_9323/201008/2010082909434077.mp3";
// 声明已经读过的长度变量
private int hasRead = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pb1 = (ProgressBar) findViewById(R.id.progressBar1);
tv1 = (TextView) findViewById(R.id.textView1);
//
pb2 = (ProgressBar) findViewById(R.id.progressBar2);
tv2 = (TextView) findViewById(R.id.textView2);
//
download(downloadFile, root, pb1, tv1);
download(downloadFile1, root, pb2, tv2);
}
private void download(String url, String targetPath, ProgressBar pb,
TextView tv) {
//构造方法
DownloadThread dt = new DownloadThread(url, targetPath, pb, tv);
dt.start();
}
// 自定义一个Handler类，处理线程消息
public class MyHandler extends Handler {
private ProgressBar progressBar;
private TextView textView;
// 通过构造函数来确定给哪个ProgressBar刷新
public MyHandler(ProgressBar progressBar, TextView textView) {
this.progressBar = progressBar;
this.textView = textView;
}
public void handleMessage(Message msg) {
this.progressBar.setProgress(msg.arg1);
this.textView.setText(msg.arg1 + "%");
super.handleMessage(msg);
}
}
// 下载线程
public class DownloadThread extends Thread {
private String url = "";
private String targetPath = "";
private int hasDownload = 0;
private int len = -1;
private byte buffer[] = new byte[4 * 1024];
private int size = 0;
private int rate = 0;
private MyHandler myHandler = null;
private Message msg = null;
private ProgressBar pb = null;
private TextView tv = null;
public DownloadThread(String url, String targetPath, ProgressBar pb,
TextView tv) {
this.url = url;
this.targetPath = targetPath;
this.pb = pb;
this.tv = tv;
myHandler = new MyHandler(this.pb, this.tv);
}
public void run() {
String targetFileName = this.targetPath
+ this.url.substring(this.url.lastIndexOf("/") + 1,
this.url.length());
File downloadFile = new File(targetFileName);
if (!downloadFile.exists()) {
try {
downloadFile.createNewFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
URL fileUrl = new URL(this.url);
HttpURLConnection conn = (HttpURLConnection) fileUrl
.openConnection();
// 获取文件大小
size = conn.getContentLength();
InputStream is = conn.getInputStream();
OutputStream os = new FileOutputStream(targetFileName);
while ((len = is.read(buffer)) != -1) {
os.write(buffer);
hasDownload += len;
rate = (hasDownload * 100 / size);
msg = new Message();
msg.arg1 = rate;
myHandler.sendMessage(msg);
System.out.println(rate + "%");
}
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
最后看看效果图吧：

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